Well at least we can look at this document for Surrounding Missourians and know the worst case scenario right.

Worst CaseJune 2007 brought a simulated big 7.7 quake. Here are damage estimates (PDF) to bridges and the river itself in case a 7.7 happened. Losses could exceed a billion dollars per county. Summary of worst case scenario per state. Regional leaders are pushing for a 4-lane bridge across the Mississippi at Helena AR, 60 miles south of Memphis. Photos of Mississippi River Bridges Top of Page